Characterization of wild type and ∆hupS strains of Anabaena siamensis TISTR 8012. Comparison of growth rate between wild type and the ∆hupS strains when cells were grown in either BG11 (A) or BG110 (B) medium, means ± S.D. (n=3). Error bars are included in the graphs, some may be smaller than the symbols used. The morphology of wild type (C) and ∆hupS strain (D) of A. siamensis TISTR 8012 cells observed under Scanning Electron Microscope (SEM) grown without the addition of N-source (BG110 medium).